I am interested in doing something like the following.
\documentclass{article}
\usepackage{amsmath}
\newenvironment{customeq}{\begin{equation}\begin{split}}{\end{split}\end{equation}}
\begin{document}
This is an equation.
\begin{customeq}
x=5
\end{customeq}
\end{document}
However, when I try to do this, I get an error saying that \begin{split} has been ended by \end{customeq}. Is there a way to get around this issue?
